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  • Tomato receptor FLAGELLIN-SENSING 3 binds flgII-28 and activates the plant immune system. 2016

    Hind S. R., S. R. Strickler, P. C. Boyle, D. M. Dunham, Z. Bao, I. M. O'Doherty, J. A. Baccile, J. S. Hoki, E. G. Viox, C. R. Clarke, B. A. Vinatzer, F. C. Schroeder and G. B. Martin
    Nature Plants 2,  16128
    Full text...
  • Detecting N-myristoylation and S-acylation of host and pathogen proteins in plants using click chemistry. 2016

    Boyle, P. C., S. Schwizer, S. R. Hind, C. M. Kraus, S. de la Torre Diaz, B. He and G. B. Martin
    Plant Methods 12:38
    Full text...
  • iTAK: a program for genome-wide prediction and classification of plant transcription factors, transcriptional regulators, and protein kinases. 2016

    Zheng, Y., C. Jiao, H. Sun, H. G. Rosli, M. A. Pombo, P. Zhang, M. Banf, X. Dai, G. B. Martin, J. J. Giovannoni, P. X. Zhao, S. Y. Rhee and Z. Fei
    Molecular Plant 16,  30223-4
    Full text...
  • High-throughput CRISPR vector construction and generation of tomato hairy roots for the characterization of DNA modifications. 2016

    Jacobs, T. B. and G. B. Martin
    Journal of Visualized Experiments 110,  e53843
    Full text...
  • A novel method of transcriptome interpretation reveals a quantitative suppressive effect on tomato immune signaling by two domains in a single pathogen effector protein. 2016

    Worley, J. N., Pombo, M. A., Zheng, Y., Dunham, D. M., Myers, C. R., Fei, Z., Martin, G.
    BMC Genomics 10.1186,  s12864-016-2534-4
    Full text...
  • Natural variation in tomato reveals differences in the recognition of AvrPto and AvrPtoB effectors from Pseudomonas syringae. 2016

    Kraus, C. M., Munkvold, K. R., Martin, G. B.
    Molecular Plant 10.1016,  j.molp.2016.03.001
    Full text...
  • Identification of a candidate gene in Solanum habrochaites for resistance to a race 1 strain of Pseudomonas syringae pv. tomato. 2015

    Bao, Z., Meng, F., Strickler, S. R., Dunham, D. M., Munkvold, K. R., Martin, G. B.
    The Plant Genome 10.3835,  plantgenome2015.02.0006
    Full text...
  • Pseudomonas syringae pv. tomato DC3000 type III secretion effector polymutants reveal an interplay between HopAD1 and AvrPtoB. 2015

    Wei H. L., Chakravarthy, S., Mathieu, J., Helmann, T. C., Stodghill, P., Swingle, B., Martin, G. B., Collmer, A.
    Cell Host & Microbe 10.1016,  j.chom.2015.05.007
    Full text...
  • Greasy tactics in the plant–pathogen molecular arms race. 2015

    Boyle, P.C., and Martin, G.B.
    Journal of Experimental Botany 10.1093,  jxb/erv059
    Full text...
  • The SGN VIGS tool: user-friendly software to design virus-induced gene silencing (VIGS) constructs for functional genomics. 2015

    Fernandez-Pozo, N., Rosli, H.G., Martin, G.B., and Mueller, L.A.
    Molecular Plant 3,  486-488
    Full text...
  • Pto kinase binds two domains of AvrPtoB and its proximity to the effector E3 ligase determines if it evades degradation and activates plant immunity. 2014

    Mathieu, J., Schwizer, S., Martin, G.B.
    PLoS Pathogens 10,  e1004227
    Full text...
  • Comparative genomics and phylogenetic discordance of cultivated tomato and close wild relatives. 2014

    Strickler, S.R., Bombarely, A., Munkvold, J.D., Menda, N., Martin, G.B., and Mueller, L.A.
    PeerJ PrePrints 2,  e377v1https://peerj.com/preprints/377v1/
  • Transcriptomic analysis reveals tomato genes whose expression is induced specifically during effector-triggered immunity and identifies the Epk1 protein kinase which is required for the host response to three bacterial effector proteins. 2014

    Pombo, M.A., Zheng, Y., Fernandez-Pozo, N., Dunham, V., Fei, Z., and Martin, G.B.
    Genome Biology 15,  492
    Full text...
  • Nonhost Resistance of Tomato to the Bean Pathogen Pseudomonas syringae pv. syringae B728a Is Due to a Defective E3 Ubiquitin Ligase Domain in AvrPtoBB728a. 2013

    Chien, C.F., Mathieu, J., Hsu, C.H., Boyle, P., Martin, G.B., and Lin, N.C.
    Molecular Plant-Microbe Interactions 26,  387-397
    Full text...
  • Allelic variation in two distinct Pseudomonas syringae flagellin epitopes modulates the strength of plant immune responses but not bacterial motility. 2013

    Clarke, C.R., Chinchilla, D., Hind, S.R., Taguchi, F., Miki, R., Ichinose, Y., Martin, G.B., Leman, S., Felix, G., and Vinatzer, B.A.
    New Phytologist 200,  847-860
    Full text...
  • The Tomato Calcium Sensor Cbl10 and Its Interacting Protein Kinase Cipk6 Define a Signaling Pathway in Plant Immunity. 2013

    de la Torre, F., Gutierrez-Beltran, E., Pareja-Jaime, Y., Chakravarthy, S., Martin, G.B., and del Pozo, O.
    Plant Cell 25,  2748-2764
    Full text...
  • Thymoquinone causes multiple effects, including cell death, on dividing plant cells. 2013

    Hassanien, S.E., Ramadan, A.M., Azeiz, A.Z.A., Mohammed, R.A., Hassan, S.M., Shokry, A.M., Atef, A., Kamal, K.B.H., Rabah, S., Sabir, J.S.M., Abuzinadah, O.A., El-Domyati, F.M., Martin, G.B., and Bahieldin, A.
    Comptes Rendus Biologies 336,  546-556
    Full text...
  • Transcriptomics-based screen for genes induced by flagellin and repressed by pathogen effectors identifies a cell wall-associated kinase involved in plant immunity. 2013

    Rosli, H. G., Zheng, Y., Pombo, M. A., Zhong, S., Bombarely, A., Fei, Z., Collmer, A., and Martin, G.B.
    Genome Biology 14,  R139
    Full text...
  • Salmonella colonization activates the plant immune system and benefits from association with plant pathogenic bacteria. 2013

    Meng, F., Altier, C., and Martin, G.B.
    Environmental Microbiology 15,  2418-2430
    Full text...
  • The Tomato Fni3 Lysine-63-Specific Ubiquitin-Conjugating Enzyme and Suv Ubiquitin E2 Variant Positively Regulate Plant Immunity. 2013

    Mural, R.V., Liu, Y., Rosebrock, T.R., Brady, J.J., Hamera, S., Connor, R.A., Martin, G.B., and Zeng, L.R.
    Plant Cell 25,  3615-3631
    Full text...
  • Two leucines in the N-terminal MAPK-docking site of tomato SlMKK2 are critical for interaction with a downstream MAPK to elicit programmed cell death associated with plant immunity. 2013

    Oh, C.S., Hwang, J., Choi, M.S., Kang, B.C., and Martin, G.B.
    FEBS Letters 587,  1460-1465
    Full text...
  • Plant programmed cell death caused by an autoactive form of Prf is suppressed by co-expression of the Prf LRR domain. 2012

    Du, X.R., Miao, M., Ma, X.R., Liu, Y.S., Kuhl, J.C., Martin, G.B., and Xiao, F.M.
    Molecular Plant 5,  1058-1067
    Full text...
  • A draft genome sequence of Nicotiana benthamiana to enhance molecular plant-microbe biology research. 2012

    Bombarely, A., Rosli, H.G., Vrebalov, J., Moffett, P., Mueller, L.A., and Martin, G.B.
    Molecular Plant-Microbe Interactions 25,  1523-1530
    Full text...
  • The beta-subunit of the SnRK1 complex is phosphorylated by the plant cell death suppressor Adi3. 2012

    Avila, J., Gregory, O.G., Su, D.Y., Deeter, T.A., Chen, S.X., Silva-Sanchez, C., Xu, S.L., Martin, G.B., and Devarenne, T.P.
    Plant Physiology 159,  1277-1290
    Full text...
  • Type III secretion and effectors shape the survival and growth pattern of Pseudomonas syringae on leaf surfaces. 2012

    Lee, J., Teitzel, G.M., Munkvold, K., del Pozo, O., Martin, G.B., Michelmore, R.W., and Greenberg, J.T.
    Plant Physiology 158,  1803-1818
    Full text...
  • Suppression and Activation of the Plant Immune System by Pseudomonas syringae Effectors AvrPto and AvrPtoB. 2012

    Martin, G.
    Effectors in Plant-Microbe Interactions 0: Wiley-Blackwell,  121-154
    Full text...
  • Molecular Mechanisms Involved in the Interaction Between Tomato and Pseudomonas syringae pv. tomato. 2012

    Velasquez, A.C., and Martin, G.B.
    Molecular Plant Immunity. 0: Wiley-Blackwell,  187-209
    Full text...
  • A tomato LysM receptor-like kinase promotes immunity and its kinase activity is inhibited by AvrPtoB. 2012

    Zeng L., Velasquez, A.C., Munkvold, K.R., Zhang, J., and Martin, G.B.
    The Plant Journal 69,  92-103
    Full text...
  • Tomato 14-3-3 protein TFT7 interacts with a MAP kinase kinase to regulate immunity-associated programmed cell death mediated by diverse disease resistance proteins. 2011

    Oh, C.S., and Martin, G.B.
    Journal of Biological Chemistry 286,  14129-14136
    Full text...
  • Effector-triggered immunity mediated by the Pto kinase. 2011

    Oh, C.S., and Martin, G.B.
    Trends in Plant Science 16,  132-140
    Full text...
  • Genetic disassembly and combinatorial reassembly identify a minimal functional repertoire of type III effectors in Pseudomonas syringae. 2011

    Cunnac, S., Chakravarthy, S., Kvitko, B.H., Russell, A.B., Martin, G.B., and Collmer, A.
    Proceedings of the National Academy of Sciences 108,  2975-2980
    Full text...
  • Structural analysis of Pseudomonas syringae AvrPtoB bound to host BAK1 reveals two similar kinase-interacting domains in a type III effector. 2011

    Cheng, W., Munkvold, K.R., Gao, H., Mathieu, J., Schwizer, S., Wang, S., Yan, Y.B., Wang, J., Martin, G.B., and Chai, J.
    Cell Host Microbe 10,  616-626
    Full text...
  • Endosome-associated CRT1 functions early in resistance gene-mediated defense signaling in Arabidopsis and tobacco. 2010

    Kang, H.G., Oh, C.S., Sato, M., Katagiri, F., Glazebrook, J., Takahashi, H., Kachroo, P., Martin, G.B., and Klessig, D.F.
    Plant Cell 22,  918-936
    Full text...
  • Two virulence determinants of type III effector AvrPto are functionally conserved in diverse Pseudomonas syringae pathovars. 2010

    Nguyen, H.P., Yeam, I., Angot, A., and Martin, G.B.
    New Phytologist 187,  969-982
    Full text...
  • Methods to study PAMP-triggered immunity using tomato and Nicotiana benthamiana. 2010

    Nguyen, H.P., Chakravarthy, S., Velasquez, A.C., McLane, H.L., Zeng, L., Nakayashiki, H., Park, D.H., Collmer, A., and Martin, G.B.
    Molecular Plant Microbe Interactions 23,  991-999
    Full text...
  • Identification of Nicotiana benthamiana genes involved in pathogen-associated molecular pattern-triggered immunity. 2010

    Chakravarthy, S., Velasquez, A.C., Ekengren, S.K., Collmer, A., and Martin, G.B.
    Molecular Plant Microbe Interactions 23,  715-726
    Full text...
  • A secreted effector protein (SNE1) from Phytophthora infestans is a broadly acting suppressor of programmed cell death. 2010

    Kelley, B.S., Lee, S.J., Damasceno, C.M.B., Chakravarthy, S., Kim, B.D., Martin, G.B., and Rose, J.K.C.
    Plant J. 62,  357-366
    Full text...
  • Tomato 14-3-3 protein 7 positively regulates immunity-associated programmed cell death by enhancing protein abundance and signaling ability of MAPKKK {alpha}. 2010

    Oh, C.S., Pedley, K.F., and Martin, G.B.
    Plant Cell 22,  260-272
    Full text...
  • Phosphorylation of the Pseudomonas syringae effector AvrPto is required for FLS2/BAK1-independent virulence activity and recognition by tobacco. 2010

    Yeam, I., Nguyen, H.P., and Martin, G.B.
    Plant Journal 61,  16-24
    Full text...
  • Virus-induced gene silencing (VIGS) in Nicotiana benthamiana and tomato. 2009

    Velasquez, A.C., Chakravarthy, S., and Martin, G.B.
    J. Vis. Exp. 28,  1292
    Full text...
  • Assay for pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) in plants. 2009

    Chakravarthy, S., Velasquez, A.C., and Martin, G.B.
    Journal of Visualized Experiments 31,  1442
    Full text...
  • Deletions in the repertoire ofPseudomonas syringae pv. tomato DC3000 type III secretion effector genes reveal functional overlap among effectors. 2009

    Kvitko, B.H., Park, D.H., Velasquez, A.C., Wei, C.F., Russell, A.B., Martin, G.B., Schneider, D.J., and Collmer, A.
    PLoS Pathogens 5,  e1000388
    Full text...
  • Crystal structure of the complex between Pseudomonas effector AvrPtoB and the tomato Pto kinase reveals both a shared and a unique interface compared with AvrPto-Pto. 2009

    Dong, J., Xiao, F.M., Fan, F.X., Gu, L.C., Cang, H.X., Martin, G.B., and Chai, J.J.
    Plant Cell 21,  1846-1859
    Full text...
  • Bacterial effectors target the common signaling partner BAK1 to disrupt multiple MAMP receptor-signaling complexes and impede plant immunity. 2008

    Shan, L.B., He, P., Li, J.M., Heese, A., Peck, S.C., Nurnberger, T., Martin, G.B., and Sheen, J.
    Cell Host & Microbe 4,  17-27
    Full text...
  • A bacterial E3 ubiquitin ligase targets a host protein kinase to disrupt plant immunity. 2007

    Rosebrock, T. R., Zeng, L., Brady, J.J., Abramovitch, R.B., Xiao, F., and Martin, G.B.
    Nature 448,  370-374
    Full text...
  • A Bacterial Inhibitor of Host Programmed Cell Death Defenses Is an E3 Ubiquitin Ligase. 2006

    Janjusevic, R., Abramovitch, R.B., Martin, G,B, and Stebbins, C.E.
    Science 311,  222-226
    Full text...
  • Host-Mediated Phosphorylation of Type III Effector AvrPto Promotes Pseudomonas Virulence and Avirulence in Tomato. 2006

    Anderson, J. C., Pascuzzi, P.E., Xiao, F., Sessa, G., and Martin, G.B.
    Plant Cell 18,  502-514
    Full text...
  • Type III Effector AvrPtoB Requires Intrinsic E3 Ubiquitin Ligase to Suppress Plant Cell Death and Immunity. 2006

    Abramovitch, R. B., Janjusevic, R., Stebbins, C.E., and Martin, G.B.
    Proceedings of the National Academy of Sciences U S A 103,  2851-2856
    Full text...
  • Bacterial elicitation and evasion of plant innate immunity. 2006

    Abramovitch, R. B., Anderson, J.C., and Martin, G.B.
    Nature Reviews Molecular Cell Biology 7,  601-611
    Full text...
  • Specific bacterial suppressors of MAMP signaling upstream of MAPKKK in Arabidopsis innate immunity. 2006

    He, P., Shan, L., Lin, N.-C., Martin, G.B., Kemmerling, B., Nurnberger, T., and Sheen, J.
    Cell 125,  563-575
    Full text...
  • MAPKKKα is a Positive Regulator of Cell Death Associated with both Plant Immunity and Disease. 2004

    del Pozo, O., Pedley, K.F., and Martin, G.B.
    EMBO Journal 23,  3072-3082
    Full text...
  • Molecular Basis of Pto-mediated Resistance to Bacterial Speck Disease in Tomato. 2003

    Pedley, K. F., and Martin, G.B.
    Annual Reviews of Phytopathology 41,  215-243
    Full text...
  • Understanding the Functions of Plant Disease Resistance Proteins. 2003

    Martin, G.B., Bogdanove, A.J., and Sessa, G.
    Annual Review of Plant Biology 54,  23-61
    Full text...
  • Pseudomonas Type III Effector AvrPtoB Induces Plant Disease Susceptibility by Inhibition of Host Programmed Cell Death. 2003

    Abramovitch, R. B., Kim, Y.J., Chen, S.R., Dickman, M.B., and Martin, G.B.
    EMBO Journal 22,  60-69
    Full text...
  • Two highly distinct Pseudomonaseffector proteins interact with the Pto kinase and activate plant immunity. 2002

    Kim, Y.-J., Lin, N.-C., and Martin, G.B.
    Cell 109,  589-598
    Full text...
  • Ancient origin of pathogen recognition specificity conferred by the tomato disease resistance gene Pto. 2001

    Riely, B., and Martin, G.B.
    Proceedings of the National Academy of Sciences U S A 98,  2059-2064
    Full text...
  • Thr38 and Ser198 are Pto Autophosphorylation Sites Required for the AvrPto-Pto-mediated Hypersensitive Response. 2000

    Sessa, G., D’Ascenzo, M., and Martin, G.B.
    EMBO Journal 19,  2257-2269
    Full text...
  • Recognition Specificity for the Bacterial Avirulence Protein AvrPto is Determined by Thr-204 in the Activation Loop of the Tomato Pto Kinase. 1998

    Frederick, R., Thilmony, R.L., Sessa, G., and Martin, G.B.
    Molecular Cell 2,  241-245
    Full text...
  • Initiation of Plant Disease Resistance by Physical Interaction of AvrPto and Pto Kinase. 1996

    Tang, X., Frederick, R., Halterman, D., Zhou, J., and Martin, G.B.
    Science 274,  2060-2063
    Full text...
  • The Tomato Gene Pti1 Encodes a Serine/threonine Kinase That is Phosphorylated by Pto and is Involved in the Hypersensitive Response. 1995

    Zhou, J., Loh, Y.T., and Martin, G.B.
    Cell 83,  925-935
    Full text...
  • A Member of the Tomato Pto Gene Family Confers Sensitivity to Fenthion Resulting in Rapid Cell Death. 1994

    Martin, G. B., Frary, A., Wu, T., Brommonschenkel, S., Chunwongse, J., Earle, E.D., and Tanksley, S.D.
    Plant Cell 6,  1543-1552
    Full text...
  • Map-based Cloning of a Protein Kinase Gene Conferring Disease Resistance in Tomato. 1993

    Martin, G. B., Brommonschenkel, S.H., Chunwongse, J., Frary, A., Ganal, M.W., Spivey, R., Wu, T., Earle, E.D., and Tanksley, S.D.
    Science 262,  1432-1436
    Full text...

Current Projects

  • Evolution of immunity

    Evolution of pathogen recognition and defense responses in wild species of tomato and tomato heirloom varieties.
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    Evolution of pathogen recognition and defense responses in wild species of tomato and tomato heirloom varieties.

  • Pattern-triggered immunity

    The plant immune system 1: Mechanisms underlying recognition and response to microbe-associated molecular patterns.
    Read more

    The plant immune system 1: Mechanisms underlying recognition and response to microbe-associated molecular patterns.

  • Effector-triggered immunity

    The plant immune system II: Mechanisms underlying recognition and response to pathogen effector proteins.
    Read more

    The plant immune system II: Mechanisms underlying recognition and response to pathogen effector proteins.

  • AvrPto virulence mechanisms

    Virtulence mechanisms of the AvrPto effector protein from Pseudomonas syringae pv. tomato.
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    Virtulence mechanisms of the AvrPto effector protein from Pseudomonas syringae pv. tomato.

  • AvrPtoB virulence mechanisms

    Virtulence mechanisms of the AvrPtoB effector protein from Pseudomonas syringae pv. tomato.
    Read more

    Virtulence mechanisms of the AvrPtoB effector protein from Pseudomonas syringae pv. tomato.

  • Methods to study plant immunity

    Development of methods and resources to study the plant immune system.
    Read more

    Development of methods and resources to study the plant immune system.

  • Nicotiana benthamiana genome project

    Nicotiana benthamiana genome project.
    Read more

    Nicotiana benthamiana genome project.

Intern Projects

Investigating pathogen virulence mechanisms using novel isolates of Pseudomonas syringae pv. tomato collected during a recent outbreak of bacterial speck disease in New York.  Identifying and characterizing immunity-associated genes from wild relatives of tomato.

The Martin laboratory studies the molecular basis of plant immunity and bacterial pathogenesis. Our focus is on the infection of tomato by Pseudomonas syringae pv. tomato as this process results in bacterial speck, an economically important disease, and also serves as a powerful model system for understanding fundamental mechanisms involved in plant-pathogen interactions. On the plant side, we identify and characterize genes, proteins and molecular mechanisms that play a role in host immunity and susceptibility. This work relies on natural variation for these traits that is present in cultivated tomato and in the 12 wild relatives of tomato that occur in South America. On the bacterial side, we study the proteins and associated mechanisms that the pathogen uses to interfere with the plant immune response. For the characterization of both plant and bacterial genes and proteins, we use a variety of experimental approaches including biochemistry, bioinformatics, genetics, genomics, molecular biology, and structural biology.

Examples of research projects for undergraduates in my laboratory include: 1) molecular characterization of novel isolates of Pseudomonas syringae pv. tomato collected during a recent outbreak of bacterial speck disease in New York; and 2) Identifying and characterizing immunity-associated genes from wild relatives of tomato. For more information about the Martin lab, please visit the various sections on this page or the Plant Pathology website.

Click the links to return to the Intern FacultyInternship Program,  Apply for an Internship pages on the BTI website.



    • Technology Area: Biotic Stress – Disease
    • Title: Nucleic acids encoding proteins with pathogen resistance activity and plants transformed therewith
    • US Patent/Application(s): 7,138,569
    • Publication: EMBO 2003
    • Technology Area: Biotic Stress – Disease
    • Title: Gene conferring disease resistance to plants by responding to an avirulence gene in plant pathogens
    • US Patent/Application(s): 5,648,599
    • Publication: Science 1993
    • Technology Area: Biotic Stress – Disease
    • Title: Nucleic acids encoding proteins with pathogen resistance activity and plants transformed therewith
    • US Patent/Application(s): 6,653,533
    • Publication: EMBO 1997
    • Technology Area: Biotic Stress – Disease
    • Title: Bacterial effector proteins which inhibit programmed cell death
    • US Patent/Application(s): 7,888,467
    • Publication: PNAS 2002
    • Technology Area: Biotic Stress – Disease
    • Title: Flagellin-sensing 3 ('fls3') protein and methods of use
    • US Patent/Application(s): PCT/US2015/039520
    • Publication: Science 2016
    • Technology Area: Biotic Stress – Disease
    • Title: Increased Resistance to Race 1 Pseudomonas via Modulation of the Rph1
    • US Patent/Application(s): 15/254,370
    • Publication: The Plant Genome 2015

Research Utilization

Bacterial Pathogenesis and the Plant Immune Response

Infectious diseases caused by pathogenic bacteria, fungi, oomycetes, viruses, and nematodes pose major economic and environmental challenges to agriculture throughout the world. It is estimated that 15% of food, fiber, and fuel crops is lost annually to diseases worldwide. One way to address this problem is to develop plant varieties that are inherently more resistant to diseases as a result of classical plant breeding or genetic engineering.

Research in the Martin lab is focused on understanding the molecular details of the infection process as well as the host immune response, from the perspective of both the pathogen and the plant. On the pathogen side, the lab studies the causative agent of speck disease in tomato, Pseudomonas syringae pv. tomato. As part of its infection process, this bacterial pathogen delivers a large number of virulence proteins directly into the plant cell where they interfere with the host immune system. The lab is determining which features of these virulence proteins are responsible for undermining host immunity and investigating the mechanisms they use to compromise specific host proteins. This research lays the foundation for developing genetic resistance in plants that avoids or counteracts the activities of virulence proteins. Discoveries from this work could have implications in both agriculture and medicine as it has recently become apparent that many disease-causing organisms of plants and humans use fundamentally similar virulence mechanisms to infect their hosts.

On the plant side, the lab uses tomato because it is the natural host for Pseudomonas syringae and it is an economically important and experimentally tractable plant species. A major goal has been to determine the structural basis of the interactions between pathogen and host proteins. This knowledge is expected to enable the design of host proteins that evade interference by pathogen virulence strategies, resulting in plants with more durable, broad-spectrum disease resistance.

In the near term, the research will add to the understanding of pathogenesis and plant immunity not only in the tomato – Pseudomonas syringae system but also in other important vegetable crops. Moreover, because it is now apparent that all plants (both monocots and dicots) appear to use fundamentally similar resistance mechanisms, the research is relevant to many economically important plant species and to the control of diseases caused by diverse pathogens.

Three projects with potential application in the Ag and Pharma industry are described below.

1)    Plant Disease Resistance: Engineering the plant BAK1 gene to enhance PAMP-triggered immunity. (Include link to slide deck).

To infect plants, Pseudomonas syringae pv. tomato delivers ∼30 type III effector proteins into host cells, many of which interfere with PAMP-triggered immunity (PTI). One effector, AvrPtoB, suppresses PTI using a central domain to bind to the host BAK1 protein, a kinase that functions with several pattern recognition receptors to activate defense signaling. The structure of the AvrPtoB-BAK1 interaction surface has been solved, and AvrPtoB mutations at the interface have been shown to disrupt bacterial virulence. These results suggest approaches for altering the plant BAK1 protein to increase plant resistance to this bacterial pathogen. Though this work is most immediately applicable to tomato, analogous approaches to disrupt host:pathogen protein interactions can be envisioned for other host:pathogen interactions.

2)    Therapeutic Proteins: Effector proteins that can modulate programmed cell death (PCD) and immune responses in diverse eukaryotes.

Programmed cell death is an important physiological process and is in fact required for maintenance of a healthy organism. PCD is well-conserved across evolution, from bacteria and plants to humans. A number of neurological diseases, including Parkinson’s and Huntington’s disease, are linked to an abnormal increase in PCD in neurological tissues. PCD is also a major component of the plant immune response to bacterial infection. Pathogenic bacteria have developed mechanisms to counteract this plant immune response. The Martin lab has discovered a number of bacterial effectors involved in PCD. One such effector is AvrPtoB (US patent number 7,888,467), which has been shown to prevent PCD in plants and other eukaryotic organisms.   Given the conservation of these types of proteins, this or related effector proteins could prove to be useful in the treatment and prevention of diseases related to an abnormally high rate of PCD or other diseases related to disorders of the immune system.

3)    Vaccine and Protein Production: Enhancing accumulation of proteins in diverse eukaryotic expression systems.

The ability to express recombinant proteins in eukaryotic cells is the basis for the

production of many vaccines and industrial enzymes It is also an essential step in fundamental studies of protein structures important in medicine and agriculture. However, expressing large amounts of protein is often challenging. The effector protein AvrPtoB is a potent suppressor of programmed cell death (PCD) induced during the plant immune response. It also suppresses PCD induced by expression of foreign proteins in plants. Furthermore, AvrPtoB suppresses PCD in yeast induced by hydrogen peroxide or menadione (vitamin K), suggesting that targets of effector proteins may be highly conserved across evolutionary space. The Martin lab has shown that AvrPtoB suppresses PCD that is induced by the expression of certain vaccine proteins in N. benthamiana, resulting in enhanced accumulation of the vaccine protein in this transient plant expression system. Thus, AvrPtoB, and presumably many other effector proteins, have the potential to enhance the synthesis of “hard-to-express” proteins in diverse eukaryotic expression systems.

Collaboration and Consulting Opportunities

  • Engineering plant disease resistance: effector-triggered immunity and basal immunity

Collaborations and Consulting

In the News

Enabling Technologies

  • Nicotiana benthamiana

    [caption id="attachment_12158" align="alignright" width="385"] Click image to link to featured Nicotiana benthamiana publication >[/caption] Bioinformatics Tools BLAST tool VIGS Tool CRISPR-P Tool CCTop CRISPR tool Genome sequence Gene annotation Metabolic Pathways Proteomics Databases Genome Browser VIGS: genes to phenotypes database N. benthamiana Experimental Protocols and Resources Agroinfiltration - Agroinfiltration of Read more »

Research Overview

How do bacteria infect plants and how do plants defend themselves from such attacks?

The Martin laboratory studies the molecular basis of bacterial infection processes and the plant immune system. The research focuses on speck disease which is caused by the infection of tomato leaves with the bacterial pathogen Pseudomonas syringae pv. tomato. This is an economically important disease that can decrease both the yield and quality of tomato fruits. It also serves as an excellent system for studying the mechanisms that underlie plant-pathogen interactions and how they have evolved. Many experimental resources including an increasing number of genome sequences are available for both tomato and P. s. pv.tomato. Current work relies on diverse experimental approaches involving methods derived from the fields of biochemistry, bioinformatics, cell biology, forward and reverse genetics, genomics, molecular biology, plant breeding, plant pathology and structural biology.

In the tomato-Pseudomonas interaction, the plant responds rapidly to a potential infection by detecting certain conserved molecules expressed by the pathogen. At this stage the pathogen uses a specialized secretion system to deliver virulence proteins, such as AvrPto and AvrPtoB, into the plant cell. These proteins suppress early host defenses and thereby promote disease susceptibility. Some tomato varieties express a resistance gene, Pto, which encodes a protein that detects the presence of AvrPto or AvrPtoB and activates a second strong immune system that halts the progression of bacterial speck disease.

The Martin lab is currently studying many aspects of the molecular mechanisms that underlie the bacterial infection process and the plant response to infection. One project takes advantage of the genetic natural variation present in wild relatives of tomato to identify new genes that contribute to plant immunity. These genes provide insights into the plant immune system and also can be bred into new tomato varieties to enhance disease resistance. A second project relies on next-generation sequencing methods to identify tomato genes whose expression increases during the interaction with P. s. pv. tomato. The expression of these genes is then reduced by using virus-induced gene silencing or they are mutated using CRISPR/Cas9 to test whether they make a demonstrable contribution to immunity. A third project uses photo-crosslinking and other biochemical methods to characterize plant proteins that play a direct role in recognizing the conserved bacterial molecules that activate the early plant immune system.

The long-term goal in this research is to use the knowledge gained about the molecular basis of plant-pathogen interactions to develop plants with increased natural resistance to diseases. Such plants would require fewer applications of pesticides producing economic and environmental benefits while providing food for consumers with less pesticide residue.